I don't think this is the best example.
1. A private directly after boot camp will be earning (pre-tax) a little over $19,000.
2. Although I think America's obsession with the NFL is unhealthy, the player is an investment that makes the teams money. I don't believe that it is unjust that the players make huge amounts of money. The teams would be cheating the players if they paid them $18,000 a year.
3. I think a better example of the injustice would be the fact that U.S. Senators make almost $200,000 a year. Basic pay, nothing special. A soon as they are elected they make about 180k the first year. That's where the injustice is.